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EEE 325 Control Systems
Lecture 01
-
Introduction
Muhammad Rizwan Azam
COMSATS Institute of Information Technology (CIIT)
Islamabad, Pakistan.
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Instructor Details
(Muhammad Rizwan Azam)• Educational Background
o PHD .. (Control Systems)
o MS (Control Systems)
o BSc Eng. (Electronics)
• Contact Details
o Room # 316, EE Block
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Marks Distribution (Theory)
Sessional -1 10%
Sessional 2 15%
Quizzes (4) 15%
Assignments (4) 10%
Terminal Exam 50%
Note:Quizzes will be announced as well un announced.
Expect a quiz after submission of assignment.
Copied assignments and assignments submitted after the due
date will be marked zero.
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Topics
to be Covered
1. Introduction and classification of everyday control systems .(1 week)
2. The Laplace transform ,Inverse Laplace transform and solution to
differential equations.(1 week)
3. Mathematical modeling of electrical, mechanical and electromechanical
systems. (1 weeks)4. Block Diagram reduction techniques and Signal Flow graphs-Mason gain
formula.(1 week)
5. Time response of first order and second order systems.(1 week)
6. Effects of poles and zeroes on system response. (1 week)
7. Steady state error analysis and design. (1 week)
8. Routh-Hurwitz criterion for stability. (1 week)
9. Introduction to design using root locus method and Analysis.(1 week)
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Topics
to be Covered
10. Frequency domain analysis, Bode analysis, Technique of drawing Bode
plot. Phase margin, Gain margins and Design using Bode plots .(2 weeks)
11. Introduction to Nyquist analysis, complex analysis, Encirclement and
enclosure of poles and zeros, Principle of Argument. Stability analysis, Gain
margins and phase margins.(2 weeks)12. State space, Introduction to state space analysis of systems presented by
Transfer function. Controllability and Observability. Solution of Time
invariant state equations.(2 weeks)
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Course Material
• Textbook
Ogata K. (2002). Modern Control Engineering (5thEd), Prentice Hall.
•References Books1. Norman S. Nise, Benjamin Cummings, “Control
Systems Engineering”, 6th edition
2. Richard C. Dorf and Robert H. Bishop, “Modern
Control Systems”, Addison Wesley, 12th Edition
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Control System
• System, A collection of components which are coordinated
together to perform a function.
• Control is the process of causing a system variable to conform
to some desired value.
• A control system provides an output or response for a given
input or stimulus
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Systems
• Definition of Controls revolve around Systems.
• Identify systems in this room
o Air-conditioners
o Bracket fans
o Amplifiers
o Humans (Combination of sub-systems)
o Power Supply of a PC
o Multimedia
o Mobile Phones
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Some other Systems
• Aircrafts, Missiles
• Planes and ships at sea
• Automotive
•Space Shuttles
• Nuclear Reactors
• Industrial Processes
• Robots
• Human Systems
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Control System Classification•
An open-loop control system utilizes an actuating device to control the process directly without using feedback.
• A closed-loop feedback control system uses a measurement of the
output and feedback of the output signal to compare it with the desired
output or reference.
Actuating
DeviceProcess Output
Desired Output
Response
Desired
OutputResponse
Measurement
OutputController ProcessComparison
Single Input Single Output (SISO) System
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1. Open Loop Control System
• In an open loop control system, the input to the plant doesnot in any way depend on the current and past values of the
output of the plant.
• Relatively simple and consequently low cost with
generally good reliability.
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Examples of Open Loop
• Motor
• Heater /boiler
• Cooking Oven
• Dish Washer
• Washing Machine
• Toaster
• Water valve system in a pool or sink
• Sprinkler System
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Example 1 – DC Motor Turntable
Open-Loop Control System
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Example 2: Missile Launcher System
Open-Loop Control System
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Disadvantage of Open Loop
• Rely totally in calibration, and cannot effectively deal
with exogenous disturbances.
• They can not effectively deal with changes in the
process.• Can not deal with uncertainty.
• Can not stabilize an unstable system.
• Often in accurate since there is no correction for error.
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2. Closed Loop Control System
• Closed loop control system make the control system robust
to uncertainty and disturbances.
• It senses the output of the system and adjust the control input
using feedback rules, which are based on how the system
output deviates from the system behaves.
• The feedback helps compensate for the differences, if the
system behaves slightly differently than the model.
• Relatively accurate in matching the actual to the required
values.
• More complex, and more expensive, grater chance of
breakdown due to number of components.
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Closed Loop
• A closed-loop control system is one in which the control action
is somehow dependent on the output.
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Basic Elements of a Closed Loop
Control system
• Comparison element
• Control element
•Correction Element
• Process element
• Measurement element
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Example of Closed Loop
• Guided missiles
• Automatic gain control in radio receivers
• Temperature Control
• Satellite tracking antenna
• Automatic Car Cruise System
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Example 1 – DC Motor Turntable
Closed-Loop Feedback Control System
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Missile Launcher System
Closed-Loop Feedback Control System
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Control System Classification
Desired
Output
Response
Measurement
Output
VariablesController Process
Multi Input Multi Output (MIMO) System
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Purpose of Control Systems
i. Power Amplification (Gain)
o Positioning of a large radar antenna by low-powerrotation of a knob
ii. Remote Control
o Robotic arm used to pick up radioactive materials
iii. Convenience of Input Form
o Changing room temperature by thermostat position
iv. Compensation for Disturbanceso Controlling antenna position in the presence of large
wind disturbance torque
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Control System Componentsi. System, plant or process
o To be controlled
ii. Actuators
o Converts the control signal to a power signal
iii. Sensors
o Provides measurement of the system output
iv. Reference input
o Represents the desired output
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General Control System
Sensor
Actuator ProcessController ++
Set-point
or
Reference
input
Actual
Output
Error
Controlled
Signal
Disturbance
Manipulated
Variable
Feedback Signal
+
-
++
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Further Reading…• Chapter 1
i. Nise N.S. (2004). Control System Engineering (4th Ed),John Wiley & Sons.
ii. Dorf R.C., Bishop R.H. (2001). Modern Control
Systems (9th Ed), Prentice Hall.